Roller drive for developing unit



March 1, 1966 osw ETAL 3,237,830

ROLLER DRIVE FOR DEVELOPING UNIT Filed Nov. 3.5, 1963 2 Sheets-Sheet 1 INVENTORS OBERT A. OSWALD RANK P. DEVOL m/wm ATTORNEYS March I, 1966 OSWALD ETAL 3,237,830

ROLLER DRIVE FOR DEVELOPING UNIT Filed Nov. 13, 1965 2 Sheets-Sheet 2 INVENTOR. ROBERT A OSWALD BY FRANK P. DEVOL {WW3 Emma A TTORNE Y8 United States Patent 3,237,830 ROLLER DRIVE FOR DEVELOPING UNIT Robert A. Oswald and Frank P. De Vol, both of 5701 W. Adams Blvd, Los Angeles, Calif. Filed Nov. 13, 1963, Ser. No. 323,300 2 Claims. (Cl. 226109) This invention relates to an improved drive mechanism for film transfer rollers on a developing tank.

In developing motion picture, the long strip of film is generally transferred through a series of sideby-side developing tanks. The film travels up and down between upper drive shaft and lower transfer shaft associated with each tank. In transferring film from tank-to-tank, the chemical baths cause the film to soften and stretch while the drying process causes it to shrink. If a direct coupling were used between the drive means and rollers, the soft stretched film would become slack on the rollers creating a possibility of the film coming off the roller. In addition, driving friction between roller and film surface would be reduced resulting in possible slippage between roller surface and film surface thereby resulting in abrasion of the soft emulsion. When the film dries, the shrinkage can create increased tension on the film and result in film breakage.

An object of this invention is to provide an improved roller drive which will solve the above problems.

It is another object of the invention to provide a roller drive for a developing unit including a plurality of commonly driven drive shafts each having a plurality of rollers slidably stacked for relative rotation thereon; wherein a simple clutch plate means exerts a relatively constant frictional force on each roller for normally rotating the rollers under relatively constant speed and torque force while yet permitting independent relative rotation between individual rollers when abnormal torque forces are applied to them.

A feature and advantage of this invention resides in the fact that the driving force applied to the film is sub stantially evenly divided among all the rollers and not concentrated at any roller and that the driving force on any one roller can never exceed a predetermined level.

Another object of this invention is to provide an im proved film driving means for a developing tank in which each transfer roller is clutch driven by a pair of disks of plastic material having a relatively constant co-etfect of friction over wide operating ranges.

Another object of this invention is to provide a simple clutch mechanism for the roller drive on a film developing unit in which a plurality of alternately stacked rollers and plastic clutch disks are forced axially into intimate contact with one another to provide uniform frictional drive of the rollers.

Still another object of this invention is to provide clutched film drive means of the above type in which the first rollers on the first drive shaft are of a smaller diameter than the remaining rollers. Wit-h this smaller diameter and resultant slower peripheral speed the film is metered into the developing unit at a relatively slower rate than the remaining larger diameter rollers peripheral speed. Thus the tendency of each larger diameter roller to pull slightly faster on the film to maintain it under tension.

Other objects and advantages of this invention will become apparent upon reading the following description and referring to the enclosed drawings in which:

FIG. 1 is a top plan view of the roller drive and developing tank;

FIG. 2 is a side elevational view of the invention taken along line 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary top view of the drive 3,237,830 Patented P/lar. 1, 1%66 means showing the details of the clutch mechanism and one roller;

FIG. 4 is a cross-sectional view of one clutch and roller means taken along the lines 44 of FIG. 3;

FIG. 5 is a top view similar to FIG, 3 but showing the diameter of roller 21(1 of slightly smaller diameter than the remaining rollers. The remaining part of the structure remains exactly the same as FIG. 3 and bears identical reference numerals.

As illustrated generally in FIGS. 1 and 2, there is provided a film developing unit having a plurality of film drive means D through D; for transferring a strip of film F through the side-by-side developing tanks A, B and C. The continuous strip of film F is transferred consecutively from tank A, to tank B, to tank C by alternately passing the film over the first roller 21a on drive means D under the first roller on a lower transfer shaft (not shown) back up and over the second roller 21!; on drive means D down under a second lower roller and so on.

As the outer roller 21d on the first drive shaft D receives the film, it transfers it to the outer roller 22d on second drive means D Film F travels down drive means D from roller to roller in much the same manner as previously discussed for drive means D The inner roller 22a adjacent support wall 12 transfers film F to the first roller 23a on the next adjacent drive means D In this transfer, film F spans the separating wall 13 between adjacent tanks A and B. The above transfer procedure is continued throughout the remaining set of drive means D through D and tanks B and C. In removing the finished film from the tank, roller 28a on drive means D feeds the film down to a lower roller where it is passed under and upward and fed to roller 14 mounted on support wall 12 In order to support the drive means D through D in horizontally extending relationship above the open tops of the developing tank, a support wall 12 extends vertically from the back of the developing tank. A plurality of spaced-apart apertures are formed in the wall at substantially equal intervals. Individual ones of cylindrical hearing means 31 to 38 are weldably secured to support wall 12 in co-axial alignment with each aperture. Individual ones of drive shafts 41 to 48 are rotatably mounted in annular relationship Within the bearing means and apertures to thus be supported in cantilever relationship to extend above the open tops of the tank.

Each drive shaft has a sprocket wheel or gears 51 to 53 secured to one end on the reaward side of support wall 12.

A power source for driving these sprockets such as the electrical motor E is mounted on a stand 14 at the rear of support wall 12. In order to rotate all of the drive means D to D in unison, a common drive chain 15 is connected to the teeth of sprocket wheel 51 on motor drive shaft 41 and commonly passed to all of the remaining sprockets 52 to 58. Thus all drive shafts rotate in unison to provide a uniform drive rate across the row of tanks.

Referring to the more detailed illustrations of FIGS. 3 and 4, it is seen that a drive means, such as D includes a generally cylindrical drive shaft 41, upon which are slidably stacked alternate film transfer rollers 21a through 21d and clutch plates 101a and 101a. One end of drive shaft 4-1 has a reduced radius cylindrical rod 71 secured in substantially co-axial alignment thereto. The other end of drive shaft 41 has a sprocket wheel 51 secured to it by means of a set screw 15 or other conventional locking device.

The vertical support wall 12 has a generally cylindrical drive shaft supporting bearing 31 weldably secured to project horizontally from it. A central cylindrical passageway 31a extends horizontally through the bearing 31 v) and is axially aligned with an aperture 61 in support wall 12. Drive s haft 41 projects horizontally through the aperture 61 and passageway 31a and is rotatably supported above the open-top of tank A.

A plurality of film transfer rollers 21a to 21d are slidably stacked at spaced intervals on drive shaft 41. As illustrated in FIG. 4, each roller is generally cylindrical in shape having a channel shaped peripheral surface defined by two edge lips 92 and 93 which act to hold film F Within the confines of the channel. A concentric cylindrical passageway 90 having a slightly larger diameter than shaft 41 extends axially through the roller. In stacking this roller, shaft 41 extends through passageway 96 in such a manner that shaft 41 and roller 21d can rotate relative to one another. Since other rollers 2111 through 210 are identical to roller 21d in both shape and operation, they need not be described in detail. It should be noted however that the diameter of rollers 21a and 21b can be made smaller than the other rollers for purposes of metering the film into the developing unit at a relatively slow speed.

In order to drive rollers 21a to 21d in unison, a clutch plate is positioned on each side of individual rollers. Each individual clutch plate means consists of one of disks 101a to 101e, each of substantially identical size and dimension. The side walls of each disk are flat while a circular passageway is formed through the middle for slidably receiving drive shaft 12. Each clutch disk is made of a hard, plastic material having relatively constant, low frictional properties and is very prone to stick over a wide range of operating conditions. One plastic material having these characteristics is Du Pont Companys Teflon.

When stacking the elements on drive shaft 41, the very first element to go on is a disk 31b such as a ball bearing race or even a low friction disk of stainless steel. Thus, frictional drag between the surface of bearing 31 and plastic disk 161a is eliminated resulting in even distribution of torque down the shaft. The next element to go on drive shaft 41 is plastic clutch plate 101a which contacts the low friction disk or bearing on one face. The second face of clutch plate 101a contacts the side wall 94 of sequentially stacked roller 21a. A second clutch plate 101!) is thereafter stacked on the shaft and subsequently sandwiched between the side walls of rollers 21a and 21b. This sequence is continued until clutch plate 101@ and is stacked adjacent the side wall of the last roller 21d. The stacked elements are then capped with a spring loaded clutch pressure plate 111 in order to hold the elements in place and press them into frictional contact with each other.

The reduced radius shaft end has a threaded portion 71 formed thereon. A spiral spring 112 encircles this threaded portion 71 and extends along the shaft to pressure plate 111. In order to permit transfer of the compressional spring energy to the elements slidably stacked on shaft 41, clutch plate 111 is generally disk shaped having a concentric passageway formed through it which will slidably receive drive shaft 41. The face of the plate remote from the stacked elements has a shoulder 113 found thereon for securing the end of spring 112 in a relatively concentric relationship for even energy distribution. A first nut 114 is screwed down reduced radius rod 71 to a point where the end of spring 112 will be sufiiciently compressed. Thereafter a 'hollow cylindrical spring guide 115 is placed over nut 114 and shaft 71 with the outer end of spring 112 encircling it. Then, a stop plate 115 is stacked against spring guide 115 and nut 114 to compress the end of spring 112. Lock nut 117 is thereafter threadably jammed against them to hold all the elements in place.

During the operation of the roller drive for a developing tank, the compressional force of spring 112 exerts constant force down the shaft to thus squeeze the plastic clutch plates 101a to 101a against the side walls 94 and 25 of each of the individual rollers 21a to 21d and between the flat faces of disk 31b and clutch plate 111. The substantially constant co-efiicient of friction at the surface of the plastic clutch plates is sufficient to impart or transfer rotational energy from shaft 41 to each of the rollers 21a through 21d when power source E is turned on. As film F is passed over each of the rollers 21a to 21d, the driving force from the drive shaft is, under normal operating conditions, distributed along the film. This results from each of the individual rollers being interdriven in unison.

If, at any time, the tensional forces on any stretch of film between individual rollers becomes too great, the frictional coupling at each clutch plate is sufficiently low to allow the affected roller to rotate independently on drive shaft 41 until the abnormal force is compensated for. It can thus be seen that by this clutch arrangement, the relative rotation of any individual roller can be either forward or backward with relation to shaft 41 to thus slow down or speed up the rollers in compensating for either slack or tension due to processing of the film F. This results in a constant feed and tensioning of film tank.

Since, however, rollers 21a and 21b are slightly smaller than the remaining rollers, film F is fed into the detveloping unit at a relatively slow speed. The remaining larger diameter rollers tend to drive the film faster. As a result of this unequal driving speed, clutch slippage occurs between each adjacent roller and operates to maintain the film under slight tension.

During film processing, the exposed strip of film F is fed first to the developing, washing and fixing solutions of tanks A and B. During this step the film softens and stretches. As slack tends to develop across the rollers, certain rollers have to exert abnormal driving forces to keep the film moving. These rollers will slip or rotate relative to the drive shaft until the slack is taken up.

When the film F is fed over idler roller 15 mounted on dividing wall 16, through aperture 17, and into the drying chamber C, it shrinks and can create tensional forces as it is continuously fed through the dryer. As increasing tension develops on the leading edge of the roller because of the increasing incremental shrinkage of the tape, certain of the rollers rotate more rapidly to prevent undue tenison from developing.

Thus, any probability of tape breakage because of abnormal tension or snarling because of slack in the film is greatly reduced or eliminated. In addition, slipping or scrapping of the film surface across individual rollers is prevented under almost all conditions to thus eliminate abrasion or scratching of the soft elmusion on the surface of the film.

As can be seen in FIG. 5, roller 2111 is arranged to receive the input end of the film. Thereafter the film is travelled over similar rollers over 21b, 21c, and finally over 21d to a winding roller for removal from the system. In this embodiment roller 21a will move at a faster rate of rotation than the remaining rollers for the same rate of film movement due to its smaller diameter. With the smaller diameter the film is then metered to the processor at a slightly slower rate than the rest of the rollers are travelling. Thus, each roller is pulling slightly faster than the first roller, thereby maintaining a slight tension.

Although one embodiment of this invention has been illustrated for purposes of description, other changes can be made in the shape, material and arrangement of parts in accordance with the principle of this invention as defined by the following claims:

We claim:

1. In a motion picture film processing tank of the type having spaced apart sets of rollers over which a continuous strip of motion picture film is run for travelling through film processing areas, an improved roller combination comprising a shaft, a plurality of rollers axially slidably and rotatably mounted on said shaft, bearing means mounted on said shaft adjacent one end of the shaft to limit axial displacement of said rollers and to allow free rotational movement of the adjacent roller against said bearing means, compression means nonrotatably mounted on the opposite end of said shaft to apply pressure against said rollers toward said bearing means, clutch discs axially slidably and rotatably mounted on said shaft between each adjacent roller and between said compression means and the adjacent roller, said clutch disc formed of a material which will frictionally transmit torque under compression, and means to rotate said shaft, said compression means being urged against said rollers with force sufficient to normally cause said rollers to impart rotary motion to each other through said clutch discs and low enough to allow each roller to independently yield to rotating and drag forces caused by motion picture film travelling thereon.

2. In a motion picture film processing tank of the type having spaced apart sets of rollers over which a continuous strip of motion picture film is run for travelling through film processing areas, an improved roller combination comprising a shaft, a plurality of rollers axially slidably and rotatably mounted on said shaft, bearing means mounted on a first end of said shaft to limit axial displacement of said rollers and to allow free rotational movement of said rollers against said bearing means, compression means non-rotatably mounted on the second end of said shaft to apply frictional pressure against said rollers toward said bearing means, clutch discs axially slidably and rotatably mounted on said shaft between adjacent roller and between said compression means and the adjacent roller, said clutch discs formed of material which will frictionally transmit torque under compression, means to rotate said shaft, said compression means being urged against said rollers with force sufficient to normally cause said rollers to impart rotary motion to each other through said clutch discs and low enough to allow each roller to independently yield to rotating and drag forces caused by motion picture film travelling thereon, a continuous motion picture film Wound for unidirectional travel over each roller and means to draw the film over the rollers at the output end of the film, the roller receiving the input end of the film being of smaller diameter than the roller receiving the output end of the film, whereby in operation the roller receiving the input end will be driven by the continuous strip of motion picture film at a slower rate than the roller receiving the output end of the film to maintain the film strip traveled by the rollers under a state of tension.

References Qited by the Examiner UNITED STATES PATENTS 2,312,520 3/1943 Bradley 226109 X 2,579,741 12/1951 Houston 24255.01 2,960,280 11/ 1960 Connelly.

3,032,914 5/1962 Valle 24256.9 X

M. HENSON WOOD, JR., Primary Examiner.

SAMUEL F. COLEMAN, Examiner. 

1. IN A MOTION PICTURE FILM PROCESSING TANK OF THE TYPE HAVING SPACED APART SETS OF ROLLERS OVER WHICH A CONTINUOUS STRIP OF MOTION PICTURE FILM IS RUN FOR TRAVELLING THROUGH FILM PROCESSING AREAS, AN IMPROVED ROLLER COMBINATION COMPRISING A SHAFT, A PLURALITY OF ROLLERS AXIALLY SLIDABLY AND ROTATABLY MOUNTED ON SAID SHAFT, BEARING MEANS MOUNTED ON SAID SHAFT ADJACENT ONE END OF THE SHAFT TO LIMIT AXIAL DISPLACEMENT OF SAID ROLLERS AND TO ALLOW FREE ROTATIONAL MOVEMENT OF THE ADJACENT ROLLER AGAINST SAID BEARING MEANS, COMPRESSION MEANS NONROTATABLY MOUNTED ON THE OPPOSITE END OF SAID SHAFT TO APPLY PRESSURE AGAINST SAID ROLLERS TOWARD SAID BEARING MEANS, CLUTCH DISCS AXIALLY SLIDABLY AND ROTATABLY MOUNTED ON SAID SHAFT BETWEEN EACH ADJACENT ROLLER AND BETWEEN SAID COMPRESSION MEANS AND THE ADJACENT ROLLER, SAID CLUTCH DISC FORMED OF A MATERIAL WHICH WILL FRICTIONALLY TRANSMIT TORQUE UNDER COMPRESSION, AND MEANS TO ROTATE SAID SHAFT, SAID COMPRESSION MEANS BEING URGED AGAINST SAID ROLLERS WITH FORCE SUFFICIENT TO NORMALLY CAUSE SAID ROLLERS TO IMPART ROTARY MOTION TO EACH OTHER THROUGH SAID CLUTCH DISCS AND LOW ENOUGH TO ALLOW EACH ROLLER TO INDEPENDENTLY YIELD TO ROTATING AND DRAG FORCES CAUSED BY MOTION PICTURE FILM TRAVELLING THEREON. 